Numbers, in the order you need.

What it does

This is a number generator with three different jobs behind one input. In listmode it produces an arithmetic run: a start, an end or a count, and a step. Insequence mode it applies a named mathematical rule — squares, cubes, triangular numbers, Fibonacci, or primes. In lines mode it numbers text that already exists, which is the job people usually want when they paste a checklist into a form.

The output is plain text, one number or line per row by default. You can switch the separator to a comma or a space, add a prefix or suffix such as # or ;, pad each number with zeros, and choose how many decimal places to show. Those are formatting choices, not changes to the underlying value, so the same list can be reused in several places without regenerating it.

Three modes, three jobs

Number list

A plain range. Use it for order numbers, page numbers, auction lots, test IDs, or a countdown. Choose “from start to end” when the boundary matters, or “a fixed count” when you know how many numbers you need.

Number sequence

A rule rather than a range. Arithmetic sequences add a step; geometric sequences multiply by a ratio; squares, cubes, and triangular numbers are generated from their position; Fibonacci follows the previous two terms; primes are tested one candidate at a time.

Number my lines

Paste one item per line and add a number to each. The format can be a dot, closing parenthesis, bracketed number, colon, dash, or a custom template containing{n}. Blank lines can be skipped instead of numbered.

Formatting that survives a spreadsheet

“One per line” is the safest default because most destinations treat each line as a record. Comma-separated output is useful when the numbers are going into a sentence or a CSV field; space-separated output is useful for prose. If you choose a custom separator, remember that a trailing separator is not added automatically — the tool joins values, it does not terminate them.

• Start and step accept negative values. A step of -5 is a valid countdown from 100 to 0. A step of 0 produces the same number repeatedly, which is occasionally useful and usually a mistake.
• Padding is applied to the formatted number, not the raw number. With two decimal places and a pad width of six, 7 becomes 0007.00.
• Prefix and suffix are added to every number, including the first and last. They are not added to the whole block.
• Descending order reverses the generated values after the range is built, so the start and end labels keep their original meaning while the output runs backward.

Examples

Start: 1001
End: 1005
Prefix: INV-

INV-1001
INV-1002
INV-1003
INV-1004
INV-1005

The prefix is repeated on each line, so the result can be pasted straight into a column. If the destination already adds a prefix, leave the prefix field empty and use the raw numbers.

Rule: Square numbers
Start: 1
Terms: 6

1
4
9
16
25
36

Square numbers start from the square of the start value. Changing the start to 10 produces 100, 121, 144… which is handy when you want a sequence that begins at a particular magnitude.

Wash the car
Return the library books

Book the dentist

1. Wash the car
2. Return the library books

3. Book the dentist

The blank line stays in place but receives no number. Turn the skip option off if every line, including the empty one, should be part of the count.

Limits worth knowing

• 100,000 numbers per run. The interface stays responsive by refusing larger requests rather than freezing. For a bigger dataset, generate it in chunks or use a script.
• Fibonacci stops at the safe-integer boundary. The sequence cannot represent the next term exactly, so it stops instead of printing a rounded value that looks precise.
• Prime generation is slower by design. It tests candidates, so it is capped at 20,000 terms. Asking for the millionth prime is not a browser task.
• Floating-point ratios can surprise you. A geometric sequence with a ratio such as 1.1 may show long decimals. Set the decimal places deliberately, and do not treat the rounded display as exact arithmetic.
• Nothing is stored. A refresh clears the settings and the output. Copy or download before leaving the page.

Page updated 27 October 2026